Incremental rotational drive

ABSTRACT

Means for changing a continuous rotation at a first shaft into an incremental or stepping rotation of a second shaft with some predetermined ratio of length of increment of rotation of the second shaft per rotation of the first shaft, utilizing a scrollshaped cam to drive a racheting arrangement, whereby any partial rotation of the first shaft is inherently stored as a position of the racheting arrangement on the scroll-shaped cam. The motion of the second shaft, directly or via transmission means, can be used to drive some operating member.

United States .Patent- 1 Stothart July 24,1973

[54] INCREMENTAL ROTATIONAL DRIVE 3,344,986 10/1967 Stasenko et 235/94 R1 1 II I 1 i David Stow-H, Cheswwk, 3,328,523. 3/1323 ifciafiffifii 232/512? [73] Assi gnee: GulfResearch & Development 3390,06) 1/1970 f 74/142companyipittsburgh Pa. 3,504,206 3/1970 Fntsch 74/126 X 1 Filed: w 21971 Primary Examiner-Richard B. Wilkinson 21 A L N b: 266 AssistantExaminer-U. Weldon [1 1 pp 0 v Attorney-Meyer Neishloss et al.

[52] US. Cl. 235/94 R, 235/91 R, 235/92 C 57 I ABSTRACT 2; g 'i' 2 Meansfor changing a continuous rotation at a first 1 e o 235/92 shaft into anincremental or stepping rotation of a second shaft with somepredetermined ratio of length of increment of rotation of the secondshaft per rotation [56] References Cited of the first shaft, utilizing ascroll-shaped cam to drive UNITED STATES PATENTS a rachetingarrangement, whereby any partial rotation 2,712,899 7/ 19 55 Krtous235/91 R of the first shaft is inherently stored as a position of the2,714,049 7/1955 Gel'malm- 235/94 R racheting arrangement on thescroll-shaped cam. The v 1;; ls-iood Mal/5:4 motion of the second shaft,directly or via transmission lmmons 3,154,672 10/1964 'Larkin 235/94 R xmeans can be used to some operatmg member 3,295,756 1/1967 Kelch et al235/91 R X 14 Claims, 4 Drawing Figures mam-mums SNEU 1 BF 2 Pmmwm w3.747. 848

sum 2 or 2 FIG 4 FIG 2 I I INCREMENTAL ROTATIONAL DRIVE This application-is related to U. S. Pat. No. 3,598,283; entitled Gasoline PumpComputer, by Ronald L. Krutz and Thomas J. Villella, and also is morespecifically related to the divisional application of said patent,co-pending application Ser. No. 120,647, filed March 3, I971 entitledPulsing Mechanism, by said Krutz and Villella, now U. S. Pat. No.3,686,507. This application is also related to co-pending Ser. No.202,446 filed on the same day as this application, entitled DigitalEncoder, Especially for Mechanical Counters," by the same inventor asthis application. All of the above related inventions are assigned tothe same assignee as the present invention.

Generally, the present invention provides means to transform acontinuous or an intermittently continuous rotational motion into anincremental or stepping rotational motion. That is, the motion of oneshaft which rotates continously is changed in accordance with theteaching of the invention into rotation of a second shaft which isincremental, i.e., sporadic or stepping with the angular length of each"increment of motion of the sec.- ond shaft corresponding to some fixedamount of rotation of the first shaft. Thus, it is necessary toeffectually store'the motion of the first shaft in the apparatus of theinvention until that first shaft has moved an amount corresponding,'asper the ratio between the shafts, to one increment of motion of thesecond shaft, and to thereupon index or move the second shaft one wholeincrement all at once. The rotation of the first shaft may thencontinue, either constantly or intermittently since the storing featureof the invention accommodates either kind ofmotion equally well, untilanother incremental motion of the second shaft is required, and soforth. Y

The above identified inventions constitute the environment in which thepresent invention was developed. In the .above identified parent patent,the circuit requires a predetermined number of electrical pulses perunit volume of gasoline passing through the pump, and the invention canbe used to produce 100 electrical pulses per gallon. 100 pulses pergallon was chosen in conjunction with the nature of the parent circuitbecause the number 100 is decimal and thus easily handled, and producesa commercially acceptable accuracy. The above identified divisionalapplication is directed to an improved pulsing mechanism. The presentinvention is a conceptually different incremental drive, particularlysuited for use as a pulsing mechanism. As

will appear in more detail below, the present invention could be used toproduce virtually any number of pulses, or, more generally, any ratio ofincremental movements at a second shaft per full rotation of a firstshaft.

The present invention is a wholly mechanical means of operating theactive member in a circuit, for example, the reed switch in the gasolinepump environment identified above. Because it is wholly mechanical, theinvention operates virtually error-free, i.e., no rotation is lost, nospurious pulses are created and no pulses are lost. Because'of thisimproved accuracy, a gallon of gasoline need not be made to correspondtothe relatively large I00 pulses, but instead the invention can be addedinto existing gasoline pump dispensing computers at a location in suchcomputers wherein each revolution of some shaft, which would be thefirst or input I which:

shaft, would correspond to a larger quantity of money or of volumedispensed, e.g., l revolution per dime or per dollar'or l revolution pergallon or per tenth of a gallon.

The above identifed divisional application, in summary, comprises aninterlock of two electrical reed switches each operated by a separatemagnet, both of which magnets are mounted on a single magnet mountingblock, and arranged mechanically and electrically in such a way that theone active pulse producing reed switch is enabled by a second reedswitch and its associ- I ated magnet for only a small part of a fullrotation of the mounting block. Thus the time, as a percentage of a fullrotation of the mounting block, during which the system is susceptibleto externally induced error, such as spurious pulses created by theelectrical systems of vehicles in the area, is reduced. However, in thatsystem, there is still a possibility that the parts could stop inaposition at which the active reed switch is susceptible to externallyinduced errors. The present invention improves upon that system bymounting a magnet at the output end of the inventions incremental driveso that the reed switch which is operatively cooperable with that magnetdoes not see" a continuous motion of the magnet at all but rather sees"only quick l80 motions of the magnet, thereby virtually totallyeliminating the time, absolutely and not merely as a percentage ofrotation, during which the reed switch is not directly under theinfluence of itsoperating magnet and thus susceptible to externallyinduced errors.

The above and other advantages of the invention will be pointed out orwill become evident in the following detailed description and claims,and in the accompanying drawingalso forming a part of the disclosure, in

FIG. 1 is an end elevational view of an embodiment of the invention asit might be mounted in a gasoline pump computer; v

FIG. 2 is a right side cross-sectional view takenon line 2-2 of FIG. 1;i

FIG. 3 is a left side elevational view taken on line 3-3 of FIG. 1; and'FIG. 4 is a view similar to FIG. 3 showing a second embodiment of theinvention.

Referring nowin detail to the drawing, there is shown in FIG. 1 a pairof walls 10 and 12, which may comprise two internal walls-in aconventional gasoline pump me chanical computer, or walls added theretofor mounting the invention, or equivalent means in any other environmentin which the invention may be used. A first shaft 14 comprises the inputshaft which is to drive the incremental drive mechanism 16 of thepresent invention. The output or second shaft 18 is to be drivenincrementally or sporadically and in some ratio of angular length orincrement per rotation of the first shaft 14, all in a manner and forreasonsthat will be developed below. The angular length of rotation ofthe second 3. Means 25, comprising a conventional suitably anchored flatspring type of pawl, is provided to prevent wheel 24 from turningbackwards.

Rotatably mounted in wall 12 is a magnet shaft 26 which carries a pinion28 which meshes with the gear 22 and which carries a bar magnet 30 atits outer free end, see FIG. 2. A magnet is used at 30 in the embodimentbeing described, but any other sort of operating member for otherapplications could be used at the output of the invention. A reed switch32, of the type set forth in more detail in the two above identifiedrelated patent specifications, is mounted on the wall closely spaced tobut not touching and operatively cooperable with the magnet 30. Theparts 30 and 32 herein correspond to the parts 42 and 44 respectively inboth said specifications.

In regard to the terms first and second shafts as used herein, it willbe appreciated that in this specific embodiment the shaft 26 is in factthe output shaft since it carries the magnet 30 which operates theswitch 32. However, more generally, the shaft 18 could be thought of asthe second or the output shaft in that it will be driven incrementallyand, depending upon the ratios required, could be used directly.Transmission means comprising the gear and pinion 22 and 28 are providedas a matter of convenience in order to be able to provide more teeth onrachet wheel 24 while producing a relatively large angular rotation ofmagnet 30, 180, in response to each rotation of input shaft 14, as willappear below.

The invention comprises means to change the intermittent continuous orcontinuous rotational motion of shaft 14 into incremental rotationalmotions of shaft 18. To this end, there is provided an operating barassembly 34 which comprises a main bar member 36 which is provided witha lower end contactor portion 38 and a rachet operating pawl portion 40.If desired for other applications, suitable anti-friction means such asa yoke mounted roller, could be provided in place of the simplecontactor shown. A tension spring 42 is provided between an anchor 44fixed to wall 10 and a spring pin 46 mounted on bar 36. Spring 42 isdisposed at a suitable angle to both bias the contactor 38 against theoperating surface of scroll shaped cam 20 and to urge pawl portion 40into engagement with the teeth of rachet wheel 24. A pair of closelyspaced guide pins 48 constrain the motion of bar 36 and a second pair ofguide pins 50 defines the limits of motion of pawl portion 40 towardsand away from shaft 18. Other guide means, not shown, will be providedto constrain bar assembly 34 to its plane of operation as indicated inFIG. 1. Thus, bar 36 may be thought of as floating in that it has nofirm connection anywhere. Pins 48 serve as pivots. The pins 50 are soplaced as to stop the bar and to prevent overshoot of the rachet wheeldue to inertia.

In the specific embodiment of the invention shown and described,'theshaft 14 was connected to an existing shaft in the mechanical gasolinepump computer such that shaft 14 makes one revolution for each ten centsworth of gasoline dispensed by the pump. Such a shaft, 10 cents perturn, already exists in most conventional pump computers. As shown,rachet 24 has 10 teeth, and the gear 22 and pinion 28 are in a 5 to lratio. The height 52 of the cam 20, i.e., the change in radius from itslargest radius to its smallest radius is substantially equal to thelength along each flat 54 of each tooth of rachet wheel 24. Thus, foreach revolution of the shaft 14 carrying the cam 20 the bar 36 will beraised by the height of one tooth of wheel 24. The spring 42 moves thepawl 40 from one tooth to the next, and when the cam 20 rotates throughthe full revolution, the contactor 38 will fall off the high part of thecam and onto the low part of the cam to thereby incrementally move shaft18, with the aid of spring 42, one-tenth of a revolution per revolutionof shaft 14. The cam is undercut slightly, i.e., the height 52 is tiltedoff the radial, so that the contactor will fall off the cam all at once,and not hang up on the height. This feature is most clearly shown inFIG. 4.

Thus, shaft 18 will move incrementally rotationally in a ratio of l to10 as shaft 14 moves continuously. Of course, as is evident, thisrotation of shaft 18 could be used directly in some other application.In the specific embodiment being described, with reference to FIG. 2, itis desired to incrementally rotate pinion 28 and hence magnet 30 180 foreach full rotation of shaft 14. The five to one gear ratio between theparts 22 and 28 accomplish this goal. The ratio chain is one turn at 14produces one-tenth of a turn at 18 which produces onehalf of a turn at26. Thus, the reed switch 32 is operated, in a sure and positive'manner,at the rate of one cycle or one operation per 10 cents worth of gasolinedispensed.

It can be seen that, by the provision of a suitable number of teeth onthe rachet 24, each such suitable number corresponding to a suitableheight 52 of the operating cam 20, various different ratios between theshafts 14 and 18 can be achieved. For large changes, on the order of10:1 or more, it is preferred to use gearing at shaft 14. That is, anoutput of an increment of angular rotation of any desired length can bemade to correspond to a rotation of the input. Various other schemes tofurther increase the versatility of the invention will presentthemselves to those skilled in the art. For example, arrangements suchas transmission means 22 and 28 can change the ratio; a double or tripleor more lobed operating cam in lieu of the cam 20 could be provided; orgearing elewhere. 4

In the above-identified related inventions, the pulsing mechanism isused to produce pulses per gallon, and these pulses are counted tototalize the money value dispensed and the volume dispensed. One of thereasons that 100 pulses per gallon were used rather than 1 pulse perpenny or 1 pulse per gallon, is that that circuitry is susceptible togaining or losing 1 or 2 pulses, and since the relatively large numberof 100 pulses per gallon is used, such a relatively minor loss or gainmakes an insignificant error. The present invention, wholly mechanical,has virtually no capability of losing a pulse, short of physicalbreakage of a part, and thus very low ratios of 1 pulse per dime or perpenny or per gallon or per large fraction of a gallon can be safelyused. Generally, the output can be made to correspond to any unit valueof money or of volume. Modifications to the computing circuitry drivenby the pulses from reed switch 32 to accommodate such changes are easilywithin the expertise of those skilled in the art.

The advantage of effectual storage of a partial rotation or motion lessthan a full turn of shaft 14 is inherent in the mechanical arrangementof the parts as shown. For example, if switch 32 were in a circuit whichwas maintaining a running total of gallons dispensed, and shaft 14rotated once per gallon, then any fraction of a gallon dispensed, asbetween sales to different customers, is inherently stored in therotational operation of the cam 20 with respect to contactor member 38.Of course, the apparatus, in this example, would have to be such that itdid not reset between sales.

Referring now to FIG. 4, there is'shown a second embodiment 16a of theinvention. Insofar as possible, parts in FIG. 4 the same as or closelycorresponding to parts in FIG. 3 are indicated by the same referencenumeral followed by a. The essential difference in the two embodimentsl6 and 16a is that the preferred embodiment 16 may be thought of asusing a floating operating bar whereas the second embodiment 16a isbuilt around a pivoted operating bar. The floating bar is more versatilein regard'to ease of placement into existing computers. It lends itselfreadily to workingaround obstacles already existing in the pumpcomputer. Thus, bar 36a is pvioted to wall 10a by a pin 56. A tensionspring 58 is locatedbetween a fixed anchor 60 and a spring pin 62 on thebar 36a to urge the bar to the right towards the cam 20a. The shafts 14aand 180 are in a different relationship to each other than thecorresponding parts in FIG. 3, but such modifications may be dictated bythe particular apparatus being worked with or in any case may be easilyadjusted by .those skilledin the art. Intermediate its ends, bar 36acarries a pawl 64 which cooperates with the scroll shaped active surfaceof the cam 20a to pivot bar 36a on pin 56 between stops 48a. At itsupper end, bar 36a carries a pivot 66 to which is mounted an operatingfinger 68 which cooperates with the teeth on the rachet wheel 24a. Aspring 70 is arranged between the parts 36a and 68 to urge the finger 68into cooperative operation with the rachet wheel 24a.

While the invention has been described in detail above, it is to beunderstood that this detailed description is by way of example only, andthe protection granted is to be limited only within the spirit of theinvention and the scope of the following claims.

I claim:

1. Apparatus for converting a continuous or intermittently continuousrotation of a first shaft into an incremental rotation of a second shaftat some predetermined ratio of angular rotation per increment of thesecond shaft per full rotation of the first shaft, comprising cam meansmounted on said first shaft, lever means operated by said cam means, arachet wheel operated by said lever means, spring means for urging saidlever means into contact with both said cam means and said rachet wheel,said rachet wheel having a predetermined number of teeth, transmissionmeans operatively cooperable with said rachet wheel, and a second shaftdriven by said transmission means, an operating member mounted on saidsecond shaft, said operating member comprises a bar magnet, and anelectrical reed switch operatively cooperable with said bar magnet,wherein said cam means comprises a scroll shaped opcrating surface forcooperation with said lever means having a height between its smallestradius portion and its largest radius portion substantially equal to thelength of a flat of a tooth on said rachet wheel, and wherein said camheight isundercut slightly to cause said lever means to move readilyfrom said largest radius portion to said smallest radius portion.

2. The combination of claim 1, wherein said rachet wheel is formed with10 teeth and wherein said transmission means between said rachet wheeland said magnet is in the ratio of five to one, whereby said sec- 0ndshaft and said bar magnet turn for each full turn of said first shaft.

3. The combination of claim 2, wherein said transmission means comprisesa gear connected to said rachet wheel and a pinion on said secondshaft'in engagement with said gear.

4. The combination of claim I, said lever means comprising a floatingbar having a pawl portion cooperable with said rachet wheel andconstrained to motion between said cam means and said rachet wheel bysaid spring means and a plurality of guide pins.

5. The combination of claim 1, wherein said lever' portion-for urgingsaid finger portion into contact with said-rachet wheel.

6. The combination of claim 1, wherein said first shaft is operativelycooperable with a portion of a mechanical gasoline dispensing pumpcomputer, and wherein said first shaft rotates at the rate of lrevolution per some unit money value of gasoline dispensed by said pump,and wherein said reed switch is in a circuit for totalizing the moneyvalue of gasoline dispensed by saidpump;

7. The combination of claim 6, wherein said first shaft is a shaft ofsaid computer which rotates at the rate of l revolution per ten cents ofmoney value of gasoline dispensed.

8. The combination of claim 1, wherein said first shaft is operativelycooperable with a portion of a mechanical gasoline dispensing pumpcomputer, and

wherein said first shaft rotates at the rate of l revolution per someunit volume of gasoline dispensed by said pump, and wherein said reedswitch is in a circuit for totalizing the volume of gasoline dispensedby said pump.

9. The combination of claim 8, wherein said first shaft is a shaft ofsaid mechanical computer which rotates at the rate of l revolution pergallon of gasoline dispensed by said pump.

10. A method of operating an electrical reed switch from a first shaftat the rate of one cycle of the reed switch per rotation of the firstshaft comprising the steps of operating rachet means by 'cam meansmounted on said first shaft, operating transmission means by said rachetmeans, mounting a bar magnet on the output end of said transmissionmeans in operative cooperation with' said reed switch, and selecting theproportions of said cam means and said rachet means and the ratio ofsaid transmission means such that said magnet will turn 180 for eachfull rotation of said first shaft and only turns said 180 at thecompletion of each full rotation of said first shaft, and such thatmotions of said first shaft less than a full revolution are stored, aspositions of said rachet means on said cam means.

11. Apparatus for converting a continuous or intermittently continuousrotation of a first shaft into an incremental rotation of a second shaftat some predetermined ratio of angular rotation per increment of thesecond shaft per-full rotation of the first shaft, comprising cam meansmounted on said first shaft, lever means operated by said cam means, arachet wheel operated. by said lever means, spring means for urging saidlever means into contact with both said cam means and said rachet wheel,said rachet wheel having a predetermined number of teeth, transmissionmeans-operatively cooperable with said rachet wheel, a second shaftdriven by said transmission means, a bar magnet mounted on said secondshaft, an electrical reed switch operatively cooperable with said barmagnet, wherein said first shaft is operatively cooperable with aportion of a mechanical gasoline dispensing pump computer, and whereinsaid first shaft rotates atthe rate of l revolution per some unit money'value of gasoline dispensed by said pump, and wherein said reed switchis in a circuit for totalizing the money value of gasoline dispensed bysaid pump.

12. The combination of claim 11, wherein said first shaft is a shaft ofsaid computer which rotates at the rate of l revolution per 10 cents ofmoney value of gasoline dispensed.

13. Apparatus for converting a continuous or intermittently continuousrotation of a first shaft into an incremental rotation of a second shaftat some predetermined ratio of angluar rotation per increment of thesecond shaft per full rotation of the first shaft, comprising cam meansmounted on said first shaft, lever means operated by said cam means, arachet wheel operated by said lever means, spring means for urging saidlever means into contact with both said cam means and said rachet wheel,said rachet wheel having a predetermined number of teeth, transmissionmeans operatively cooperable with said rachet wheel, a second shaftdriven by said transmission means, a bar magnet mounted on said secondshaft, an electrical reed switch operatively cooperable with said barmagnet, wherein said first shaft is operatively cooperable with aportion of a mechanical gasoline dispensing pump computer, and whereinsaid first shaft rotates at the rate of one revolution per some unitvolume of gasoline dispensed by said pump, and wherein said reed switchis in a circuit for totalizing the volume of gasoline dispensed by saidpump.

14. The combination of claim 13, wherein said first shaft is a shaft ofsaid mechanical computer which rotates at the rateof 1 revolution pergallon of gasoline dispensed by said pump.

1. Apparatus for converting a continuous or intermittently continuousrotation of a first shaft into an incremental rotation of a second shaftat some predetermined ratio of angular rotation per increment of thesecond shaft per full rotation of the first shaft, comprising cam meansmounted on said first shaft, lever means operated by said cam means, arachet wheel operated by said lever means, spring means for urging saidlever means into contact with both said cam means and said rachet wheel,said rachet wheel having a predetermined number of teeth, transmissionmeans operatively cooperable with said rachet wheel, and a second shaftdriven by said transmission means, an operating member mounted on saidsecond shaft, said operating member comprises a bar magnet, and anelectrical reed switch operatively cooperable with said bar magnet,wherein said cam means comprises a scroll shaped operating surface forcooperation with said lever means having a height between its smallestradius portion and its largest radius portion substantially equal to thelength of a flat of a tooth on said rachet wheel, and wherein said camheight is undercut slightly to cause said lever means to move readilyfrom said largest radius portion to said smallest radius portion.
 2. Thecombination of claim 1, wherein said rachet wheel is formed with 10teeth and wherein said transmission means between said rachet wheel andsaid magnet is in the ratio of five to one, whereby said second shaftand said bar magnet turn 180* for each full turn of said first shaft. 3.The combination of claim 2, wherein said transmission means comprises agear connected to said rachet wheel and a pinion on said second shaft inengagement with said gear.
 4. The combination of claim 1, said levermeans comprising a floating bar having a pawl portion cooperable withsaid rachet wheel and constrained to motion between said cam means andsaid rachet wheel by said spring means and a plurality of guide pins. 5.The combination of claim 1, wherein said lever means comprises a barpivoted at one end and having a pawl portion cooperable with said cammeans and a finger portion cooperable with said rachet wheel, and secondspring means between said bar and said finger portion fOr urging saidfinger portion into contact with said rachet wheel.
 6. The combinationof claim 1, wherein said first shaft is operatively cooperable with aportion of a mechanical gasoline dispensing pump computer, and whereinsaid first shaft rotates at the rate of 1 revolution per some unit moneyvalue of gasoline dispensed by said pump, and wherein said reed switchis in a circuit for totalizing the money value of gasoline dispensed bysaid pump.
 7. The combination of claim 6, wherein said first shaft is ashaft of said computer which rotates at the rate of 1 revolution per tencents of money value of gasoline dispensed.
 8. The combination of claim1, wherein said first shaft is operatively cooperable with a portion ofa mechanical gasoline dispensing pump computer, and wherein said firstshaft rotates at the rate of 1 revolution per some unit volume ofgasoline dispensed by said pump, and wherein said reed switch is in acircuit for totalizing the volume of gasoline dispensed by said pump. 9.The combination of claim 8, wherein said first shaft is a shaft of saidmechanical computer which rotates at the rate of 1 revolution per gallonof gasoline dispensed by said pump.
 10. A method of operating anelectrical reed switch from a first shaft at the rate of one cycle ofthe reed switch per rotation of the first shaft comprising the steps ofoperating rachet means by cam means mounted on said first shaft,operating transmission means by said rachet means, mounting a bar magneton the output end of said transmission means in operative cooperationwith said reed switch, and selecting the proportions of said cam meansand said rachet means and the ratio of said transmission means such thatsaid magnet will turn 180* for each full rotation of said first shaftand only turns said 180* at the completion of each full rotation of saidfirst shaft, and such that motions of said first shaft less than a fullrevolution are stored as positions of said rachet means on said cammeans.
 11. Apparatus for converting a continuous or intermittentlycontinuous rotation of a first shaft into an incremental rotation of asecond shaft at some predetermined ratio of angular rotation perincrement of the second shaft per full rotation of the first shaft,comprising cam means mounted on said first shaft, lever means operatedby said cam means, a rachet wheel operated by said lever means, springmeans for urging said lever means into contact with both said cam meansand said rachet wheel, said rachet wheel having a predetermined numberof teeth, transmission means operatively cooperable with said rachetwheel, a second shaft driven by said transmission means, a bar magnetmounted on said second shaft, an electrical reed switch operativelycooperable with said bar magnet, wherein said first shaft is operativelycooperable with a portion of a mechanical gasoline dispensing pumpcomputer, and wherein said first shaft rotates at the rate of 1revolution per some unit money value of gasoline dispensed by said pump,and wherein said reed switch is in a circuit for totalizing the moneyvalue of gasoline dispensed by said pump.
 12. The combination of claim11, wherein said first shaft is a shaft of said computer which rotatesat the rate of 1 revolution per 10 cents of money value of gasolinedispensed.
 13. Apparatus for converting a continuous or intermittentlycontinuous rotation of a first shaft into an incremental rotation of asecond shaft at some predetermined ratio of angluar rotation perincrement of the second shaft per full rotation of the first shaft,comprising cam means mounted on said first shaft, lever means operatedby said cam means, a rachet wheel operated by said lever means, springmeans for urging said lever means into contact with both said cam meansand said rachet wheel, said rachet wheel having a predetermined numberof teeth, transmission means operatively cooperable with said rachetwheel, a second shafT driven by said transmission means, a bar magnetmounted on said second shaft, an electrical reed switch operativelycooperable with said bar magnet, wherein said first shaft is operativelycooperable with a portion of a mechanical gasoline dispensing pumpcomputer, and wherein said first shaft rotates at the rate of onerevolution per some unit volume of gasoline dispensed by said pump, andwherein said reed switch is in a circuit for totalizing the volume ofgasoline dispensed by said pump.
 14. The combination of claim 13,wherein said first shaft is a shaft of said mechanical computer whichrotates at the rate of 1 revolution per gallon of gasoline dispensed bysaid pump.